Vinylamine copolymers prepared by the Hofmann reaction were functionalized by amidification with cinnamoyl chloride. The resulting photosensitive polymers, which are the nitrogen analogues of poly(vinylcinnamate), can be prepared with various contents of cinnamamide side groups. The polymers exhibit a marked hydrophilicity and undergo efficient crosslinking upon exposure to 250-300 nm UV light. The sensitivity S expressed in cm(2).J(-1) was shown to be higher for a given conf ent, tau, in cinnamamide groups expressed in mol.g(-1) when the residual vinyl amine units are in the ammonium form. The dependence of S upon tau was of the second order for the free base form of the photopolymers, but a higher order with S approximately proportional to tau(3) for the hydrochloride form of the photosensitive polymers.